The only threat they posses is that they can bring their bigger brothers against us and that's just it. Without them, they'd get slapped like the spoiled kid they are, not even worthy of a punch.
We shouldn't look at this at what we might risk, but as what we might gain, and it isn't just some technology or money. Hard power is not the only way to get what you want, in fact, about 90% of the time its only use is to back your soft power. More European countries we develop ties with, the more power we are going to get. Italy isn't France or Greece, their goals don't always align with those two, especially in the Mediterranean. We already have a good relationship with Spain, and it has been getting better with UK, adding Italy to that list would be great for us.